The present invention concerns game balls and more specifically balls that are intended to roll or travel through the air in an erratic path.
A number of balls have been designed to behave erratically. For example, U.S. Pat. No. 3,498,613 (Dreyer) shows a tethered ball which contains an inner, smaller ball to induce erratic movement.
Similarly, U.S. Pat. No. 4,194,737 (Farmer) shows a variety of ball designs wherein a hollow body encloses a spherical weight. Additionally, magnets are used to cause the body and weight to interact less predictably.
The need for such an interaction between the inner and outer balls can be understood with reference to French Patent No. 846,327 (Ratignier) which seems to indicate that a hollow outer ball with a spherical inner ball is actually highly stable, rather than erratic, particularly when used on rough surfaces. This is apparently due to the low center of gravity of the entire ball.
Others have included objects inside of balls, but for other purposes. Such balls are shown in U.S. Pat. Nos. 2,351,762 (Hoover); 3,655,197 (Milbaum) and 4,300,767 (Reed et al.).